A standard shop-type punching or riveting machine normally has a lower part that is fixed and that serves to support the workpiece being punched or riveted and an upper part that is vertically displaceable by means of a heavy-duty hydraulic actuator toward and away from the lower part. In a riveting machine the lower part normally carries a rivet-setting tool and the upper part constitutes a rivet anvil, or vice versa. In a punching machine the lower part normally is provided with a die and the upper part with a punch. It is also known to provide such a machine, normally on its upper part, with an embossing tool that serves to mark a workpiece in relief.
It has been suggested to combine the functions of these machines so that a single basic unit can perform several functions. This is normally done by means of one or more turrets mounted on the machine parts and each carrying a plurality of different tools. In order to switch from the one type of tool to another the turret or turrets must be rotated to bring the desired tools into alignment. It is also known to provide a quick-release chuck on one of the parts so that various tools can quickly be mounted on it or taken off it.
Such devices have several disadvantages. First of all the relatively complex turret arrangements frequently are only suitable for light-duty application. They cannot withstand substantial forces as needed, for example, in punching metal stock for subsequent setting of rivets. Furthermore they are relatively complicated and expensive. What is more these machines rarely can be adapted for two different types of operations, such as punching and riveting, due to the different requirements and shapes of the different tools needed.